1. Field of the Invention
The present invention relates to a synthetic resin film covered heat insulating/sound absorbing material of inorganic fibers which can eliminate a worker""s discomfort due to dispersion of inorganic fibers and a method of producing the same.
2. Discussion of Background
Inorganic fiber mats made of inorganic fibers such as glass wool, rock wool or the like have widely been used as heat insulating/sound absorbing materials for buildings such as houses. The heat insulating/sound absorbing material is generally so made that front and rear surfaces of an inorganic fiber mat and both side surfaces along the direction of a longer side of the mat are covered with skin materials in order to eliminate discomfort such as an irritating feeling to a worker due to the dispersion of inorganic fibers in a construction site, and to provide the inorganic fiber mat with moisture-proofness. In a typical method of producing the heat insulating/sound absorbing materials of inorganic fibers, inorganic fiber mats are continuously delivered;
skin materials are respectively supplied to front and rear surfaces of the inorganic fiber mats; both side portions of the skin materials for covering the front and rear surfaces are jointed so that the front and rear surfaces and both side surface along the direction of a longer side of the inorganic fiber mats are covered; and
the skin materials are cut off together with the inorganic fiber mats at a predetermined length.
In the heat insulating/sound absorbing material of inorganic fibers produced by the above-mentioned typical method, end surfaces of each of the inorganic fiber mats where the skin materials are cut off at a predetermined length, namely, both side surfaces along the direction of a shorter side of each of the inorganic fiber mats are not covered with the skin materials, and the end surfaces of the inorganic fiber mats are in an exposed state. Accordingly, a worker""s discomfort due to the dispersion of inorganic fibers at the exposed portions was unavoidable.
Further, when the heat insulating/sound absorbing material having an exposed portion in an inorganic fiber mat was used as a heat insulating/sound absorbing material for a wall or the like in a house, moisture enters into the wall from the interior side to the exterior side and enters into the heat insulating/sound absorbing material from the exposed portion of the inorganic fiber mat. Then there is a danger of condensation when the outer temperature decreases. The condensation reduces the heat insulating performance of the mat. Further, when the condensation continues for a long term, the foundation and beams of the house will decay.
In order to solve the above-mentioned problem, Japanese unexamined publication JP-A-6-79849 discloses that an elongated inorganic fiber mat is cut off at a predetermined length and the cut inorganic fiber mats are successively delivered; thermoplastic resin sheets are supplied to front and rear surfaces of the mats; both side portions of the thermoplastic resin sheets in the direction of a longer side of the mats are melt-bonded; the thermoplastic resin sheets at the front and rear sides are melt-bonded at portions between adjacent inorganic fiber mats followed by cutting whereby the entire surface of the inorganic fiber mat is covered with the thermoplastic resin sheets, and portions of the thermoplastic resin sheets which have not been subjecting to melt-bonding are used as air communication holes.
However, the heat insulating/sound absorbing material of inorganic fibers disclosed in Japanese unexamined publication JP-A-6-79849 has problems as follows because the thermoplastic resin sheets which cover the inorganic fiber mat are mutually melt-bonded.
A thermoplastic resin sheet used generally for a skin material has a certain amount of variation in thickness at local portions. Accordingly, when a melt-bonding operation is conducted while conditions for melt-bonding such as temperature, pressure and so on are kept constant, the melt-bonding may be insufficient due to a short of heat at a portion where the thickness of the sheet is relatively large. On the other hand, the sheet is broken before melt-bonding due to over-heating and over-pressure at a portion where the thickness is relatively small. Thus, a state of melt-bonding becomes unstable. Further, when melt-bonding is conducted for the thermoplastic resin sheets at portions between adjacent inorganic fiber mats, it takes a certain time. Accordingly, the movement of the thermoplastic resin sheets is temporarily stopped with the result that scattering of a tension in the thermoplastic resin sheets is apt to take place, which may cause an unstable melt-bonding state in the same manner as above, and wrinkles may be produced in the sheets.
Thus, in an event of insufficient melt-bonding or the breakage of the sheets which results in no melt-bonding, inorganic fibers disperse from an uncovered portion whereby a worker feels stimulation.
Further, since it takes a certain time to finish the melt-bonding of the thermoplastic resin sheets, a faster feeding speed of the thermoplastic resin sheets causes difficulty in the melt-bonding. Although the feeding speed depends on the quality and the thickness of the thermoplastic resin sheets, there is possibility of causing a trouble of melt-bonding when the feeding speed exceeds 35 m/min, for instance. Accordingly, the driving speed of the production line for the heat insulating/sound absorbing material was restricted, and therefore, productivity was low.
Further, since the melt-bonding of the thermoplastic resin sheets at both end portions along the direction of a shorter side of the inorganic fiber mats was conducted in the direction perpendicular to the feeding direction of the thermoplastic resin sheets between adjacent inorganic fiber mats i.e. in the direction perpendicular to the direction of the flow of the production line of the heat insulating/sound absorbing material of inorganic fibers, a melt-bonding device had to be moved for a predetermined time in the direction of the flow of the production line of the heat insulating/sound absorbing material in order to provide a sufficient heating-pressing time for the melt-bonding. Accordingly, the melt-bonding device should be of a special construction.
It is an object of the present invention to provide a heat insulating/sound absorbing material wherein the entire surface of an inorganic fiber mat is covered with a synthetic resin film or films while communication of air is possible and a method of producing the same at a high productivity without causing a defect of bonding in the thermoplastic resin sheets.
In accordance with a first aspect of the present invention, there is provided a synthetic resin film covered heat insulating/sound absorbing material of inorganic fibers which comprises:
an inorganic fiber mat, and a single or two synthetic resin films which cover front and rear surfaces and the both side surfaces along the direction of a longer side of the inorganic fiber mat, wherein the synthetic resin film at the front side and the synthetic resin film at the rear side respectively have extensions which extend from both sides along the direction of a shorter side of the inorganic fiber mat and which are bonded with an adhesive at mutually opposing portions so that both end surfaces along a shorter side of the inorganic fiber mat are covered with the synthetic resin films, and the inorganic fiber mat is bonded to one of the synthetic resin films and the synthetic resin films are mutually bonded in the discontinuous manners in the direction of a shorter side of the inorganic fiber mat so that air communicates through unbonded portions of the synthetic resin films.
In a second aspect of the present invention, there is provided the synthetic resin film covered heat insulating/sound absorbing material according to the first aspect wherein the inorganic fiber mat is covered with two synthetic resin films of front and rear side synthetic resin films, and the two synthetic resin films respectively have opposing side portions which are bonded along a longer side of the inorganic fiber mat.
In a third aspect of the present invention, there is provided the heat insulating/sound absorbing material according to the first aspect wherein the synthetic resin films are constituted by a single film; the inorganic fiber mat is covered in a tubular form with the single film, and both side portions of the single film are mutually bonded along the direction of a longer side of the inorganic fiber mat.
In a fourth aspect, there is provided the heat insulating/sound absorbing material according to anyone of the first to the third aspects, wherein the synthetic resin film or films are bonded in a discontinuous manner along the direction of a longer side of the inorganic fiber mat so that air communicates through unbonded portions of the synthetic resin films.
In a fifth aspect, there is provided the heat insulating/sound absorbing material according to anyone of the first to the fourth aspects, wherein the synthetic resin film or films have extensions extended from both sides along a longer side of the inorganic fiber mat and extensions extended from both sides along a shorter side of the inorganic fiber mat respectively.
In a sixth aspect, there is provided the heat insulating/sound absorbing material according to anyone of the first to the fifth aspects, wherein each of the extensions of the synthetic resin films extended from both sides along the direction of a longer side of the inorganic fiber mat is 10 mm to 100 mm.
In a seventh aspect, there is provided the heat insulating/sound absorbing material according to anyone of the first to the sixth aspects, wherein each of the extensions of the synthetic resin films extended from both sides along the direction of a shorter side of the inorganic fiber mat is 10 mm to 200 mm.
In an eighth aspect, there is provided the heat insulating/sound absorbing material according to anyone of the first to the seventh aspects, wherein the adhesive is a hot-melt type adhesive.
In a ninth aspect of the present invention, there is provided a method of producing a synthetic resin film covered heat insulating/sound absorbing material of inorganic fibers which comprises:
a step of accumulating inorganic fibers during which a binder composed mainly of a thermosetting resin is applied to the inorganic fibers; curing the binder by heating to form an accumulation of inorganic fibers in a mat-like shape; cutting the mat-like accumulation of inorganic fibers to form inorganic fiber mats, and feeding the inorganic mats at a predetermined distance;
a step of supplying two synthetic resin films so as to cover the inorganic fiber mats from the sides of front and rear surfaces of the mats while an adhesive is applied continuously or discontinuously along a longitudinal direction of the synthetic resin films to a portion in the direction of the width of at least one of the two synthetic resin films;
a step of pressing continuously a portion of the inorganic fiber mats on which the synthetic fiber films are overlaid, the portion corresponding to the portion where the adhesive is applied, whereby the inorganic fiber mats and the synthetic resin films, and mutually the synthetic resin films are bonded; and
a step of pressing the synthetic resin films at portions between adjacent inorganic fiber mats to bond them, and at the same time, the synthetic resin films are cut off over the entire width of the synthetic resin films.
In accordance with a tenth aspect of the present invention, there is provided a method of producing a synthetic resin film covered heat insulating/sound absorbing material of inorganic fibers which comprises:
a step of accumulating inorganic fibers during which a binder composed mainly of a thermosetting resin is applied to the inorganic fibers: curing the binder by heating to form an accumulation of inorganic fibers in mat-like shape; cutting the mat-like accumulation of inorganic fibers to form inorganic fiber mats, and feeding the inorganic mats at a predetermined distance;
a step of supplying a single synthetic resin film from the side of rear surface of the mats while an adhesive is applied continuously or discontinuously along a longitudinal direction of the synthetic resin film to a portion in a width direction of the synthetic resin film;
a step of bending the synthetic resin film in the direction of the width of fiber mats to cover the front and rear surfaces and both side surfaces along the direction of a longer side of the inorganic fiber mats;
a step of pressing continuously a portion of the inorganic fiber mats on which the synthetic resin film is overlaid, the portion corresponding to the portion where the adhesive is applied, whereby the inorganic fiber mats and the synthetic resin film, and an overlaid portion of the synthetic resin film are bonded; and
a step of pressing the synthetic resin film at portions between adjacent inorganic fiber mats to bond the overlaid portion, and at the same time, the synthetic resin film is cut off over the entire width of the synthetic resin film.
The kind of the inorganic fibers used for the present invention is not in particular limited, and glass wool, rock wool or the like which is usually used as a heat insulating/sound absorbing material of inorganic fibers can be used.
Further, the kind of the inorganic fiber mat is not in particular limited, and may be of the ordinarily used heat insulating/sound absorbing material made of inorganic fibers, i.e., of such a type that inorganic fibers are accumulated while a binder composed mainly of a thermosetting resin is applied to the inorganic fibers and the binder is cured by heating to thereby form a mat-like accumulation of inorganic fibers. The density of the inorganic fiber mat can be such that it is usable as the ordinary heat insulating/sound absorbing material. For example, it is preferable for the mat to be about 5 to 100 kg/m3.
The synthetic resin film for the present invention can be for covering the ordinarily used heat insulating/sound absorbing material of inorganic fibers, e.g., a thermoplastic resin film or a laminate made of polyethylene, polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate or the like, the thermoplastic resin film or a laminate on which metallic material such as aluminum is deposited or the thermoplastic resin film or a laminate on which a different kind of synthetic resin film or an aluminum foil or the like is laminated. In particular, a high density polyethylene film is preferably used.
The thickness of the synthetic resin film is preferably in a range of 10 to 50 xcexcm, more preferably, 15 to 30 xcexcm. When the thickness is less than 10 xcexcm, the tear strength is insufficient. On the other hand, when the thickness exceeds 50 xcexcm, the weight is too large.
The synthetic resin film for covering the front surface side of the inorganic fiber mat is preferably provided with a large number of apertures having a diameter of about 1 to 5 mm so that the flow-in or the flow-out of air can be easy when the heat insulating/sound absorbing material is compressed in packaging or when a package is opened to restore the shape of the heat insulating/sound absorbing material at a working site, and moisture in the heat insulating/sound absorbing material is released with an air flow.
A single synthetic resin film or two synthetic resin films may be used as long as the entire surface of the inorganic fiber mat can be covered.
The adhesive used for the present invention can be of any type as long as the synthetic resin film or films can be bonded. As examples of the adhesive used, there are a hot-melt type adhesive such as an ethylene-vinyl acetate copolymer resin or the like, a rubber cement such as a chloroprene rubber, a styrene-butadiene rubber or the like, a water-soluble adhesive such as an acrylic resin, polyvinyl alcohol or the like and an emulsion type adhesive such as an acrylic resin, polyvinyl alcohol or the like. In particular, a sticking hot-melt type adhesive is more preferable because a time for adhering is short.
The method of applying the adhesive on the synthetic resin film is not in particular limited as long as the applying is conducted uniformly. For example, a method using spray, a method of using roll coverer can be utilized. When the adhesive is to be applied discontinuously, an air atomizing method, a spiral spray method, a wide spray method or the like is preferable. In particular, the wide spray method is more preferable since the width of applying can be kept constant. In order to apply the adhesive discontinuously , a spray device should have an electromagnetic type valve at the outlet for injecting the adhesive so that the adhesive is discharged discontinuously by controlling the opening and closing operation of the valve at predetermined intervals.
In the present invention, a single synthetic resin film or two synthetic resin films are used to cover front and rear surfaces of an inorganic fiber mat as well as both side surfaces thereof along the direction of a longer side of the mat, and at the same time, the single or two synthetic resin films have extensions extended from both sides (both end surfaces) along the direction of a shorter side of the inorganic fiber mat so as to cover the both sides (the both end surfaces) along the direction of a shorter side of the mat. After the inorganic fiber mat has been covered with the synthetic resin film or films, overlapping portions of the film or films, i.e. an edge portion or portions along the direction of a longer side of the synthetic resin film or films and edge portions along the direction of a shorter side of the film or films, are bonded, whereby the inorganic fiber mat is completely covered with the synthetic resin film or films. In this case, at least one unbonded portion should be formed in the bonded portion of the film or films so that the flow-in or flow-out of air is possible when the heat insulating/sound absorbing material is compressed at a packaging time or when the package is opened to restore the shape of the heat insulating/sound absorbing material at a working site.
The unbonded portion in the synthetic resin film or films can be formed at a position where the synthetic resin film or films are in an overlapping state along the direction of a shorter side of the inorganic fiber mat and the adhesive is discontinuously applied to the overlapping portions in the direction of the width of the synthetic resin film or films. Also, the unbonded portion can be formed at a position where the synthetic resin film or films are in an overlapping state along the direction of a longer side of the inorganic fiber mat and the adhesive is applied discontinuously to the overlapping portions along the direction of a longer side of the synthetic resin film or films.
At the same time of bonding the overlapping portions of the synthetic resin film or films, the inorganic fiber mat is partially bonded to the synthetic resin film or films with use of the adhesive so that the inorganic fiber mat is prevented from moving in the synthetic resin film or films. The position of applying the adhesive is preferably at a portion which neighbors the bonded position of the synthetic film or films along the direction of a longer side of the inorganic fiber mat or a substantially central portion in the direction of a shorter side of the inorganic fiber mat so that the front surface and/or the rear surface of the inorganic fiber mat is bonded to the synthetic resin film or films. The width of the adhesive to be applied is preferably about ⅕ to xc2xd of the width of the heat insulating/sound absorbing material. For example, when the heat insulating/sound absorbing material which is ordinarily used for houses, a width of about 100 mm is preferable.
A desired amount of the adhesive per unit surface area is in a range of 1 to 10 g/m2, more preferably, 1 to 5 g/m2.
In a preferred embodiment, when the entire surface of the inorganic fiber mat is covered with the synthetic resin film or films and the mat is bonded to the film or films and the synthetic resin films are mutually bonded with the adhesive, portions of the synthetic resin film or films are extended in an ear-like form (or a flange-like form) from both sides along the direction of a longer side and both sides along the direction of a shorter side of the inorganic fiber mat respectively. When all the extended portions are connected to posts, studs, the foundation and beams with staples, a secured fixture can be obtained in comparison with a conventional inorganic fiber mat wherein only ear portions formed at two sides are used for fixing. Further, a space surrounded by the posts, the studs, the foundation and the beams can be completely isolated by means of the synthetic resin film or films whereby the invasion of moisture into the space can effectively be prevented and condensation on the posts and so on and at the inside of the inorganic fiber mat can be prevented.
It is preferable that the length of the extensions extended from both sides along the direction of a shorter side of the inorganic fiber mat is in a range of from 10 to 200 mm, and more preferably, 70 to 170 mm. When the length of the extensions of the synthetic resin film or films is less than 10 mm, it is difficult to bond the film or films with the adhesive and to cut it or them with a pressing/cutting device during manufacture process. Further, there is difficulty in stapling in the application of the heat insulating/sound absorbing material. Further, when the length of the extensions exceeds 200 mm, it is obstructive in packaging and in the application of the heat insulating/sound absorbing material in a working site, and it is unadvantageous in an economical view since an amount of the synthetic resin film used increases.
Further, the length of the extensions of the synthetic resin film or films extended from both sides along the direction of a longer side of the inorganic fiber mat is preferably 10 to 100 mm, and more preferably, 20 to 50 mm. When the length of the extensions of the film or films is less than 10 mm, the stapling of the extensions in the application of the heat insulating/sound absorbing material is difficult. On the other hand, when the length exceeds 100 mm, it is unadvantageous in an economical view since a wider synthetic resin film is required.